DUCTILIZATION OF NI3AL BY ALLOYING WITH BORON AND SUBSTITUTIONAL ELEMENTS

The effect of simultaneous alloying of boron (B) and the substitutional element (M) on the ductilization of Ni3Al was investigated by the bend test. The alloy compositions were selected by considering the substitutional mode of M, the solid solution range of Ni3Al + M and Ni3Al + B, and the deviation from stoichiometry. Ni3Al is ductilized by alloying with Zr, Hf, V, Nb, Mo, W, Co, Pd, Cu, Cr, Mn and Fe. The Ni-3(Al, M) compounds, where M substitutes exclusively for the Al atoms, are ductilized by microalloying with B on the Ni-rich side. in contrast, the (Ni, M)(3)Al compounds where M substitutes exclusively for the Ni atoms, and the (Ni, Mn)(3)(Al, Mn) + B compounds where Mn substitutes for both atoms, are ductilized by microalloying with B on both the Ni-rich and Al-rich sides. The increase or decrease in the ductile region of Ni3Al by simultaneous alloying with B and M is discussed on the basis of the formation tendency of the borides MB and MB(2).